Make fling thresholds consistent

There are 3 places we can block a fling:
- Swiping from home to all apps (through overview)
- Swiping from an app to all apps (through overview)
- Dismissing a task (in the same gesture that started by swiping down)

In all of these cases, we block the fling when crossing the threshold
to a new state (e.g. OVERVIEW), but unblock if the user pauses their
drag. With this change, the logic is consistent:
- Unblock the fling after pausing a short amount of time
- If a fling was blocked, increase the settling duration based on
  velocity

Bug: 78089840
Bug: 78658678
Change-Id: I5ef52b74229418b867b26c3c6d3db2cf6e48914b

3 files changed, 78 insertions, 22 deletions

diff --git a/src/com/android/launcher3/LauncherAnimUtils.java b/src/com/android/launcher3/LauncherAnimUtils.java
index 9869fdf7e..03ffded72 100644
--- a/src/com/android/launcher3/LauncherAnimUtils.java
+++ b/src/com/android/launcher3/LauncherAnimUtils.java
@@ -39,6 +39,9 @@ public class LauncherAnimUtils {
     public static final int SPRING_LOADED_TRANSITION_MS = 150;
     public static final int SPRING_LOADED_EXIT_DELAY = 500;
 
+    // The progress of an animation to all apps must be at least this far along to snap to all apps.
+    public static final float MIN_PROGRESS_TO_ALL_APPS = 0.5f;
+
     static WeakHashMap<Animator, Object> sAnimators = new WeakHashMap<Animator, Object>();
     static Animator.AnimatorListener sEndAnimListener = new Animator.AnimatorListener() {
         public void onAnimationStart(Animator animation) {
@@ -165,16 +168,8 @@ public class LauncherAnimUtils {
                 }
             };
 
-    public static final Property<View, Float> ELEVATION =
-            new Property<View, Float>(Float.class, "elevation") {
-                @Override
-                public Float get(View view) {
-                    return view.getElevation();
-                }
-
-                @Override
-                public void set(View view, Float elevation) {
-                    view.setElevation(elevation);
-                }
-            };
+    /** Increase the duration if we prevented the fling, as we are going against a high velocity. */
+    public static int blockedFlingDurationFactor(float velocity) {
+        return (int) Utilities.boundToRange(Math.abs(velocity) / 2, 2f, 6f);
+    }
 }
diff --git a/src/com/android/launcher3/touch/AbstractStateChangeTouchController.java b/src/com/android/launcher3/touch/AbstractStateChangeTouchController.java
index 6e48c3641..087549e2e 100644
--- a/src/com/android/launcher3/touch/AbstractStateChangeTouchController.java
+++ b/src/com/android/launcher3/touch/AbstractStateChangeTouchController.java
@@ -15,6 +15,7 @@
  */
 package com.android.launcher3.touch;
 
+import static com.android.launcher3.LauncherAnimUtils.MIN_PROGRESS_TO_ALL_APPS;
 import static com.android.launcher3.LauncherState.ALL_APPS;
 import static com.android.launcher3.LauncherState.NORMAL;
 import static com.android.launcher3.LauncherState.OVERVIEW;
@@ -32,6 +33,7 @@ import android.view.HapticFeedbackConstants;
 import android.view.MotionEvent;
 
 import com.android.launcher3.Launcher;
+import com.android.launcher3.LauncherAnimUtils;
 import com.android.launcher3.LauncherState;
 import com.android.launcher3.LauncherStateManager.AnimationComponents;
 import com.android.launcher3.LauncherStateManager.AnimationConfig;
@@ -43,6 +45,7 @@ import com.android.launcher3.anim.AnimatorSetBuilder;
 import com.android.launcher3.userevent.nano.LauncherLogProto.Action.Direction;
 import com.android.launcher3.userevent.nano.LauncherLogProto.Action.Touch;
 import com.android.launcher3.userevent.nano.LauncherLogProto.ContainerType;
+import com.android.launcher3.util.FlingBlockCheck;
 import com.android.launcher3.util.PendingAnimation;
 import com.android.launcher3.util.TouchController;
 
@@ -80,7 +83,7 @@ public abstract class AbstractStateChangeTouchController
     private float mProgressMultiplier;
     private float mDisplacementShift;
     private boolean mCanBlockFling;
-    private boolean mBlockFling;
+    private FlingBlockCheck mFlingBlockCheck = new FlingBlockCheck();
 
     private AnimatorSet mAtomicAnim;
     private boolean mPassedOverviewAtomicThreshold;
@@ -241,7 +244,7 @@ public abstract class AbstractStateChangeTouchController
             mStartProgress = mCurrentAnimation.getProgressFraction();
         }
         mCanBlockFling = mFromState == NORMAL;
-        mBlockFling = false;
+        mFlingBlockCheck.unblockFling();
     }
 
     @Override
@@ -253,16 +256,19 @@ public abstract class AbstractStateChangeTouchController
         if (progress <= 0) {
             if (reinitCurrentAnimation(false, isDragTowardPositive)) {
                 mDisplacementShift = displacement;
-                mBlockFling = mCanBlockFling;
+                if (mCanBlockFling) {
+                    mFlingBlockCheck.blockFling();
+                }
             }
         } else if (progress >= 1) {
             if (reinitCurrentAnimation(true, isDragTowardPositive)) {
                 mDisplacementShift = displacement;
-                mBlockFling = mCanBlockFling;
+                if (mCanBlockFling) {
+                    mFlingBlockCheck.blockFling();
+                }
             }
-        } else if (Math.abs(velocity) < SwipeDetector.RELEASE_VELOCITY_PX_MS) {
-            // We prevent flinging after passing a state, but allow it if the user pauses briefly.
-            mBlockFling = false;
+        } else {
+            mFlingBlockCheck.onEvent();
         }
 
         return true;
@@ -325,7 +331,7 @@ public abstract class AbstractStateChangeTouchController
         final LauncherState targetState;
         final float progress = mCurrentAnimation.getProgressFraction();
 
-        boolean blockedFling = fling && mBlockFling;
+        boolean blockedFling = fling && mFlingBlockCheck.isBlocked();
         if (blockedFling) {
             fling = false;
         }
@@ -338,14 +344,17 @@ public abstract class AbstractStateChangeTouchController
             // snap to top or bottom using the release velocity
         } else {
             logAction = Touch.SWIPE;
-            targetState = (progress > SUCCESS_TRANSITION_PROGRESS) ? mToState : mFromState;
+            float successProgress = mToState == ALL_APPS
+                    ? MIN_PROGRESS_TO_ALL_APPS : SUCCESS_TRANSITION_PROGRESS;
+            targetState = (progress > successProgress) ? mToState : mFromState;
         }
 
         final float endProgress;
         final float startProgress;
         final long duration;
         // Increase the duration if we prevented the fling, as we are going against a high velocity.
-        final long durationMultiplier = blockedFling && targetState == mFromState ? 6 : 1;
+        final int durationMultiplier = blockedFling && targetState == mFromState
+                ? LauncherAnimUtils.blockedFlingDurationFactor(velocity) : 1;
 
         if (targetState == mToState) {
             endProgress = 1;
diff --git a/src/com/android/launcher3/util/FlingBlockCheck.java b/src/com/android/launcher3/util/FlingBlockCheck.java
new file mode 100644
index 000000000..f9575b97a
--- /dev/null
+++ b/src/com/android/launcher3/util/FlingBlockCheck.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.launcher3.util;
+
+import android.os.SystemClock;
+
+/**
+ * Determines whether a fling should be blocked. Currently we block flings when crossing thresholds
+ * to new states, and unblock after a short duration.
+ */
+public class FlingBlockCheck {
+    // Allow flinging to a new state after waiting this many milliseconds.
+    private static final long UNBLOCK_FLING_PAUSE_DURATION = 200;
+
+    private boolean mBlockFling;
+    private long mBlockFlingTime;
+
+    public void blockFling() {
+        mBlockFling = true;
+        mBlockFlingTime = SystemClock.uptimeMillis();
+    }
+
+    public void unblockFling() {
+        mBlockFling = false;
+        mBlockFlingTime = 0;
+    }
+
+    public void onEvent() {
+        // We prevent flinging after passing a state, but allow it if the user pauses briefly.
+        if (SystemClock.uptimeMillis() - mBlockFlingTime >= UNBLOCK_FLING_PAUSE_DURATION) {
+            mBlockFling = false;
+        }
+    }
+
+    public boolean isBlocked() {
+        return mBlockFling;
+    }
+}